Apparatus for introducing a coolant into grinding wheels



July 10, 1945. H. J. SCHEER 2,380,332

APPARATUS FOR INTRODUCING A COOLANT INTO GRINDING WHEELS Filed May 2%. 1943 we/f' J aeer 9 k3 J or mandrel on which the wheel is mounted and Patented July 10, 1945 APPARATUS FOR INTRODUCING A COOLANT INTO GRINDING WHEELS Hubert J. Scheer, Collingswood, N. J., assignor to Abrasive Company, Philadelphia, Pa., a corporation of Pennsylvania Application May 27, 1943, Serial No. 488,754

2 Claims. (Cl. 51 267) This invention relates to grinding wheels, and more particularly to various means for effecting internal cooling of the wheels, and the work,

' during operation of the wheels.

The principal object of the present invention is to effect cooling. of a grinding wheel by percolation of a liquid coolant radially of the wheel, through the interstices of the homogeneous body of the wheel, from the center of the wheel to the peripheral face thereof, throughout the en- -tire circumference of the wheel; uniformly, by-

the bearings in hich the indle or mandrel revolve; which increases the normal useful life of the wheel, permits the wheel to be rotated at increased speeds, and eliminates bearing lubricating problems normally encountered in the operation of grinding wheels at high velocities.

Another advantage of the invention resides in the cooling of the work, at the grinding point, by the constant presence of the coolant directly beneath the work, while the work is in contact with the grinding surface of the wheel.

Another advantage of the invention resides in the quenching of sparks, or the elimination of the formation of sparks which normally result from contact between the work and the wheel.

Another advantage of the invention is that the constant outward radial percolation of the coolant discourages accumulation of work dust in the pores of the grinding face of the wheel,

thus, the wheel presents a clean surface to the work at all times, which increases the efliciency of the wheel accordingly.

The invention 'is particularly advantageous in precision grinding work, as effected by centerless grinding machines, for example, in that the respectively of wheel structures falling within the scope of the present invention.

, For the purpose of the present invention, each of the wheels disclosed in the drawing essentially is of a porous nature. Porous wheels, however, are well known in the art. Each wheel, in the present instance, may be composed, for example, of any well known abrasive substance, having any desired grain size, and a suitable bonding substance of any well known kind. In mixing the components of the wheel, prior to molding of the wheel, a suitable quantity of some form of porosity-producing substance is included with the abrasive grain and bonding components. This porosity-producing ingredient 'is subsequently eliminated from the wheel, leaving the wheel in a homogeneously porous state, in its finished form, with intercommunicating interstitial channels extending throughout the body of the wheel in all directions.

In the case of vitrified wheels, for example, wood flour may be mixed with a suitable granular abrasive substance, such as aluminum oxide, silicon carbide, etc., and a suitable ceramic bonding substance. After molding, the wheels are fired at relatively high temperatures, for example, temperatures approximating 2300 F., to effect integration of the abrasive and bonding substances. The firing of the wheels burns out the wood flour, leaving the wheel in the form of a porous homogeneous body throughout its entire mass, with the interstices created by the elimination of the wood flour affording infinitesimal channels running through all parts of the body of the wheel.

According to the present invention, it is through the above noted infinitesimal channels that a liquid coolant is caused to travel, under pressure of centrifugal force, or extraneous pressure, or both, from the center of the wheel to the working face of the wheel.

The active cutting edges of the abrasive grain on the peripheral face of the wheel are surrounded with the coolant, at the grinding point, which effects cooling of the abrasive grain, and consequently maintains the wheel at relatively low temperature.

At the same time, the presence of the coolant at the point of contact of the work with the grinding face of the wheel reduces the temperature of the infinitesimal particles or chips of material removed from the work by the aforesaid cutting edges of the abrasive grain and thus preventsthe formation of a shower of sparks from and tangentially to the peripheral face of the wheel at the point of grinding.

In order to confine the radial progression of the coolant within the body of the wheel, the opposite sides respectively, of the wheel are preferably coated or superficially impregnated with a suitable fluid-proofing substance, such, for example, as sulphur.

v The outward flow of the coolant through the interstitial channels of the body of the wheel and outwardly from the peripheral surface of the wheel, under the relatively high pressure created by the centrifugal force resulting from the high velocity at which the wheel is rotated, in addition to effecting a cooling of the abrasive grain on, the grinding face of the wheel, prevents oxidizing of the particles or chips removed from the piece of work and their consequent fluxing to the abrasive grain particles; and the pressure .of the outward radial progression of the coolant through the interstitial channels and around the exposed surfaces of the abrasive grain particles on the peripheral face of the wheel continuously removes the work chips from the face of the wheel thus keeping the working face of the wheel clean. Keeping f the work engaging face of the wheel clear of chips, substantially increases the cutting efllciency of the wheel and, at the same time, materially increases the normal life of the wheel.

In Fig. 1, a disc type of abrasive wheel I7 is shown as being provided with a central axially extending cavity 59'. The porous wheel I is mounted on the usual spindle 81 between an inner flange If and an outer flange Hi and is gripped therebetween by the usual nut I27 threaded onto the spindle 87 which forces the inner flange I01 against an annular shoulder 53 on the spindle 8a. The outer flange H7 is provided with an annular utter 331' and axial ports 327' aflording communication between said gutter and the interior of the central axially extending cavity 57'.

Immediately adjacent and in contact with the inner circular wall 237' of the central cavity 59' of the wheel la, a fine mesh metal screen 60, for example, a screen of ISO meshes per inch, more or less, depending upon the nature of the coolant employed, is provided. Preferably the mesh is so line that the molecules of the coolant would not normally pass through the screen, except under pressure such as would be exerted thereon by celrlitrifugal force set up in and by the revolving w eel.

The coolant is delivered inside the screen ring 80 through ports 321 from the annular gutter 331 to which the coolant is fed by a pipe etc. 35?

The coolant entering the cavity I1 through the ports 825 will flow across the screen 80 and become distributed across the axial dimension thereof before progressing radially outward through the porous body of the wheel Ii.

In Fig. 2, distribution of the liquid coolant across the wheel is effected by a perforated ring k in contact with the inner circular wall 23k of the central cavity 5k of the wheel lie.

The liquid coolant entering the inside of the perforated ring 8010, through the ports 32k, from the annular gutter "k, is prevented from passing between the ring 60k and the wall 2310 of the central cavity Us by means of an annular lip 8| turned inwardly from a gasket 62 placed between the flange ilk and the side 6k of the wheel Ik.

I claim:

1. The combination with a porous grinding wheel having a central axially extending cavity, a pair of flanges respectively gripping the opposite side faces of the wheel, an annular gutter formed in one of said flanges, ports affording communication between said cavity and said gutter, means for supplying a fluidic coolant to said gutter, and means within said cavity for receiving said medium from said ports and delivering it directly todeflnite localities throughout the full circumference and axial depth of said cavity for uniformly distributing said medium axially and circumferentially of said cavity.

2. The combination with a porous grinding wheel having an axially extending central cavity, a pair of flanges respectively gripping the opposite side faces of the wheel, an annular gutter formed in one of said flanges, ports affording communication between said cavity and said gutter, means for supplying a fluidic medium to said gutter, and a foraminous liner in said cavity for receiving said medium from said ports and delivering it directly to definite localities throughout the full circumference and axial depth of said cavity for uniformly distributing said medium axially and circumferentially of said cavity.

HUBERT J. SCI-IElER. 

